Question 587667
sqrt(y+15) - sqrt(y-15) = 1

sqrt(y+15) = sqrt(y-15) + 1  

square both sides:

y+15 = y-15 + 2sqrt(y-15) + 1

29 = 2sqrt(y-15)

29/2 = sqrt(y-15)

square both sides:

841/4 = y-15

y = 841/4 + 15 = 841/4 + 60/4 

y = 901/4 = 225.25